Low-oxalate diets are used primarily to control kidney stones. Approximately 1 in
every 1,000 adults is hospitalized annually in the United States for kidney stones (renal calculi). Although kidney stones
can be composed of different substances, more than 75% of the kidney stones in patients in the
United States are made of calcium oxalate. All further mention of kidney stones in this
section refers only to calcium oxalate stones. The information provided here does not apply to
other forms of kidney stones.
Avoid high-oxalate foods such as beans, spinach, chocolate, wheat, and peanuts.
Drink plenty of fluids, limit your sodium intake, and consume adequate calcium (but do not
take calcium supplements between meals).
Talk to a healthcare professional such as a doctor or a registered dietitian to make sure
you’re following the best diet for your condition before you make any changes to your
diet.
Best bets: Lean beef, pork, and lamb, vegetables like peas and lettuce, and
cheese
Why do people follow this diet?
A hereditary condition can increase the risk of forming calcium oxalate stones. Intestinal
resection, parathyroidism, and other more rare conditions also may cause renal calculi, and
dietary factors can increase or reduce the risk of forming kidney stones. A low-oxalate diet
is often prescribed for people who have increased levels of oxalic acid in their urine or who
have a history of forming kidney stones. A treatment program including a low-oxalate diet and
plenty of fluids reduces the risk of stone formation. A low oxalate diet is not always
effective in reducing urinary oxalic acid levels because most oxalate found in urine is made
in the body and does not come from the diet. People with a predisposition to stones are also
encouraged to drink plenty of fluids (3 to 4 quarts [liters] per day), limit sodium intake,
and consume adequate calcium, although calcium supplements should not be taken between
meals.
What are the symptoms?
In combination with calcium, the oxalic
acid crystallizes to form kidney stones—small pebbles that form in either the kidney or
the bladder. If these stones are small enough, they will pass out of the body without being
noticed. However if too large, they can cause severe pain, obstruction of the flow of urine,
and sometimes infection in the urinary tract.
What do I need to avoid?
Scientists once thought that the greater the oxalate level in a food, the more likely it
was to increase the risk of forming a kidney stone. However, researchers have discovered that
consumption of only certain oxalate-containing foods is likely to significantly increase
urinary oxalate. The foods reported by at least one group of researchers to cause a
significant increase in urinary oxalate include
spinach, rhubarb, beets,
nuts, chocolate, wheat bran, strawberries, peanuts,
almonds, and tea. Not every study has
found tea to significantly increase urinary oxalate. There remains no universal consensus on
which oxalate-containing foods belong on this list. Nonetheless, there is a growing awareness
that the important issue for people with a history of kidney stone formation is to avoid
certain high-oxalate foods—those that are most responsible for increasing urinary
levels of oxalate.
To avoid oxalates ask about ingredients at restaurants and others’ homes, and read
food labels. The following list is not complete. Consult with a healthcare professional before
making any significant changes to your diet.
These foods are high in oxalate (greater than 10 mg per serving):
The following are some useful resources to help you learn more about dietary prevention and
treatment of kidney stones.
The Kidney Stones Handbook: A Patient’s Guide to Hope, Cure
and Prevention by Gail Savitz, Stephen W. Leslie, Gail Golomb. Roseville, CA: Four Geez
Press, 2000.
Kidney Stones in Adults: National Kidney and Urologic Diseases
Information Clearinghouse
www.niddk.nih.gov/health/kidney/pubs/stonadul/stonadul.htm
The Oxalosis and Hyperoxaluria Foundation
www.ohf.org
Bibliography
Alpers DH, Stenson WF, Bier, DM. Manual of Nutritional
Therapeutics. 3rd ed. Boston, MA: Little, Brown and Company; 1995.
Berkow R, Fletcher AJ, et al, eds.The Merck Manual of Diagnosis
and Therapy. 15th ed. Rahway, NJ: Merck Sharp & Dohme Research Laboratories;1987.
Brinkley, LJ, Gregory J, Pak Cy. A further study of oxalate
availability in foods. J Urol 1990; 144:94–6.
Krieg C. The role of diet in the prevention of common kidney stones.
Urol Nurs 2005;25:451–7 [review].
Mahan LK, Escott-Stump S. Krause’s Food Nutrition and Diet
Therapy. 10th ed. Philadelphia, PA: W.B. Saunders Company; 2000.
Massey LK, Roman-Smith H, Sutton RA. Effect of dietary oxalate and
calcium on urinary oxalate and risk of formation of calcium oxalate kidney stones. J Am
Diet Assoc 1993; 93:901–6.
The information presented in the Food Guide is for informational purposes
only and was created by a team of US–registered dietitians and food experts. Consult
your doctor, practitioner, and/or pharmacist for any health problem and before using any
supplements, making dietary changes, or before making any changes in prescribed medications.
Information expires June 2009.
